Method and system for analyzing inventory purchasing opportunities with respect to inventory health

ABSTRACT

A method and system for determining analyzing an inventory purchasing opportunity with respect to inventory health. A method may include receiving an offer to purchase units of an inventory item via a purchasing channel for a purchase price per unit; determining a rate of sales demand of the item; and determining a breakeven holding time of existing units of the item, where a cost of holding a unit until the breakeven holding time equals, within an equality threshold, a difference between a sales channel value and the offer purchase price. The method may additionally include determining a healthy inventory level of the item that exceeds a target inventory level by a function of the sales demand rate and the breakeven holding time, and, if a current inventory level of the item exceeds the healthy level, declining to purchase units of said inventory item for the purchase price.

This application claims benefit of priority to U.S. Provisional PatentApplication No. 60/728,207 filed Oct. 19, 2005 titled “Method and Systemfor Inventory Health” which is hereby incorporated by reference hereinin its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to inventory management and, more particularly,to analysis of inventory metrics or measurements of inventory health.

2. Description of the Related Art

In order to offer customers a variety of items readily available fordelivery, many merchants (whether engaging in electronic or conventional“brick and mortar” commerce) hold various quantities of such itemswithin inventory facilities. Keeping items in inventory may serve tobuffer variations in customer demand or a manufacturer or distributor'sability to supply various items. For example, different items offeredfor sale by a merchant may have different manufacturer lead times.Holding quantities of such items as inventory may enable a merchant tooffer consistent availability of these items to customers despite thedifferent lead times.

Many merchants employ conventional inventory management schemes thatattempt simply to ensure that the inventory on hand is sufficient tocover expected customer order volumes for a particular period of time.That is, such conventional inventory management schemes focus on whetherthere is enough inventory on hand to meet projected demand. However,storing inventory is not without cost. For example, providing a physicalfacility in which to store inventory presents recurring infrastructurecosts directly attributable to the inventory items stored in thefacility. Further, while items are in storage awaiting sale, debt orcapital costs associated with acquiring the items may accumulate. Itemsbeing held in inventory may also depreciate, become obsolete, expire orspoil (e.g., in the case of perishable items), become damaged, orotherwise incur costs attributable to holding. When these variousinventory holding costs are considered, having too much inventory mayalso be a concern, as accumulating costs may erode inventory value.

However, taking holding costs into account when optimizing inventorypresents challenges. The price paid to acquire a given amount ofinventory typically represents a sunk cost that may not correlate withthe current value of that inventory, which may obscure actions that maybe necessary to maximize the current inventory value. Further, theproblem of maximizing inventory value is complicated by purchaseopportunities that, on their surface, may appear to be desirable, butwhich may actually have a deleterious effect on overall inventory value.

SUMMARY

Various embodiments of a method and system for analyzing an inventorypurchasing opportunity with respect to inventory health are disclosed.According to one embodiment, a method may include receiving an offer topurchase units of an inventory item via a purchasing channel for a givenpurchase price per unit and determining a time rate of sales demand ofunits of the given inventory item per unit of time. The method may alsoinclude determining a breakeven holding time of existing units of theinventory item, where a cost of holding a given existing unit until thebreakeven holding time equals, within an equality threshold, adifference between a sale value for sale of the given inventory itemthrough a sales channel and the purchase price specified by the offer.

The method may further include determining a healthy inventory level ofthe inventory item, where the healthy inventory level exceeds a targetinventory level by a mathematical function of the time rate of salesdemand and the breakeven holding time, and in response to determiningthat a current inventory level of the inventory item exceeds the healthyinventory level, declining to purchase the units of the inventory itemfor the given purchase price.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating one embodiment of a fulfillmentcenter.

FIG. 2 is a block diagram illustrating one embodiment of a sales channeland a disposition channel.

FIG. 3 is a flow diagram illustrating one embodiment of a method ofanalyzing inventory health.

FIG. 4 is a flow diagram illustrating one embodiment of a method ofevaluating a purchasing opportunity with respect to inventory health.

FIG. 5 is a flow diagram illustrating one embodiment of a method ofevaluating a purchasing opportunity with respect to purchase quantityand price.

FIG. 6 is a block diagram illustrating an exemplary embodiment of acomputer system.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof are shown by way ofexample in the drawings and will herein be described in detail. Itshould be understood, however, that the drawings and detaileddescription thereto are not intended to limit the invention to theparticular form disclosed, but on the contrary, the intention is tocover all modifications, equivalents and alternatives falling within thespirit and scope of the present invention as defined by the appendedclaims.

DETAILED DESCRIPTION OF EMBODIMENTS Inventory Management Using InventoryMetrics

One embodiment of a fulfillment center configured to store inventoryitems is illustrated in FIG. 1. In the illustrated embodiment,fulfillment center 10 includes a receiving area 20, a storage area 30configured to store an arbitrary number of items 35 a-n, and apacking/shipping area 40. The arrangement of the various areas withinthe illustrated embodiment of fulfillment center 10 is depictedfunctionally rather than schematically. For example, in someembodiments, it is noted that multiple different receiving areas 20,storage areas 30 and packing/shipping areas 40 may be interspersedrather than segregated. Additionally, fulfillment center 10 includes aninventory management system 50 configured to interact with each ofreceiving area 20, storage area 30 and packing/shipping area 40.

Fulfillment center 10 may be configured to receive different kinds ofitems 35 from various suppliers and to store them until a customer orderspecifying particular ones of items 35 is received. The particular items35 may then be selected from storage and sent to the customer. Thegeneral flow of items through fulfillment center 10 is indicated usingarrows. Specifically, in the illustrated embodiment, items 35 may bereceived from one or more suppliers, such as manufacturers,distributors, wholesalers, etc. at receiving area 20. In variousembodiments, items 35 may include merchandise, commodities, perishables,or any suitable type of item depending on the nature of the enterprisethat operates fulfillment center 10. Upon being received from a supplierat receiving area 20, items 35 may be prepared for storage. For example,in some embodiments items 35 may be unpacked or otherwise rearranged,and inventory management system 50 (which, as described below, mayinclude one or more software applications executing on a computersystem) may be updated to reflect the type, quantity, condition, cost orany other suitable parameters with respect to newly received items 35.It is noted that items 35 may be stocked, managed or dispensed in termsof countable, individual units or multiples of units, such as packages,cartons, crates, pallets or other suitable aggregations. Alternatively,some items 35 such as bulk products, commodities, etc. may be stored incontinuous or arbitrarily divisible amounts that may not be inherentlyorganized into countable units. Such items 35 may be managed in terms ofmeasurable quantities such as units of length, area, volume, weight,time duration or other dimensional properties characterized by units ofmeasurement. Generally speaking, a quantity of an item 35 may refer toeither a countable number of individual or aggregate units of an item 35or a measurable amount of an item 35, as appropriate.

After arriving through receiving area 20, items 35 may be stored withinstorage area 30. In some embodiments, like items 35 may be storedtogether in bins, on shelves or via other suitable storage mechanisms,such that all items 35 of a given kind are stored in one location. Inother embodiments, like items 35 may be stored in different locations.For example, to optimize retrieval of certain items 35 having highturnover within a large physical facility, those items 35 may be storedin several different locations to reduce congestion that might occur ata single point of storage.

When a customer order specifying one or more of items 35 is received,the corresponding items 35 may be selected or “picked” from storage area30. In various embodiments, item picking may range from minimallyautomated to completely automated picking. For example, in oneembodiment fulfillment center employees may pick items 35 using writtenor electronic pick lists derived from customer orders, while in anotherembodiment conveyor belts and robotics may be used to pick and transferitems 35. After the items 35 corresponding to a particular order arepicked, they may be processed at packing/shipping area 40 for deliveryto the customer. For example, items may be packaged for shipment to thecustomer using a common carrier, or simply bagged or otherwise preparedfor direct transfer to a customer, e.g., at an order pickup counter. Insome embodiments, further interaction with inventory management system50 may occur when items 35 are picked from storage area 30 and/orprocessed at packing/shipping area 40, for example to update inventoryrecords to reflect the removal of inventory, to record revenue for thesale or other transaction (e.g., lease, rental, exchange, etc.) and soforth.

Management of items 35 stored as inventory within fulfillment center 10presents complex optimization problems. Generally speaking, the level ofinventory of a given item 35 may affect the quality of serviceassociated with providing the given item to a customer. Quality ofservice may encompass factors such as general availability and selectionof items 35, timeliness of order completion, or any other factorsrelevant to a customer's perceived experience in conducting businessrelating to items 35. As an example of the interaction between inventorylevels and quality of service, if a particular item 35 ordered by acustomer is not in stock within fulfillment center 10, the customer maybe forced to wait for delivery until that particular item 35 can beobtained, or the customer may cancel the order resulting in a lost sale.Consequently, keeping a number of units of items 35 on hand may assistin the timely fulfillment of orders and increase customer satisfaction.A larger inventory, for example, may more readily accommodate unexpectedincreases in customer demand.

However, various costs are typically associated with holding items 35 instorage for any period of time. In some embodiments, holding a unit ofan item 35 in storage within storage area 30 may incur incrementalstorage costs. For example, the cost of providing fulfillment center 10in which items 35 may be stored may include recurring real estate costs(e.g., lease costs, debt service, etc.), personnel costs, facilitiescosts (e.g., utilities, maintenance, etc.) and any other costsassociated with fulfillment center 10. In one embodiment, such costs maybe incrementally apportioned to a given unit of an item 35 according toan area or volume of storage space occupied by that unit. For example,storage costs may be applied to each unit of each item 35 at a rate ofdollars per square/cubic foot of item volume per unit of storage time(day, week, month, etc.). In other embodiments, different costallocation methods may be employed. For example, in one embodiment thecosts of providing special storage or handling, such as refrigeration,controlled atmosphere, etc. may exclusively be allocated to those items35 that require such measures, rather than averaging those costs acrossall items 35. Similarly, in one embodiment, storage may includetemporary capacity (e.g., short-term leased space, seasonal overflowcapacity, etc.) as well as permanent capacity (e.g., owned space,year-round capacity, etc.), each of which may have different costcharacteristics. Correspondingly, in some such embodiments items 35stored within a particular type of facility may exclusively incur costsof the particular type of facility according to their storageutilization (e.g., area, volume, etc.). Alternatively, storage costs maybe allocated to items 35 based upon their value or sales volume asopposed to their size. In some embodiments, additional costs associatedwith obtaining a given item 35, such as transportation/handling costscharged by a supplier or incurred by eventual shipment to a customer,may be included within storage costs for that given item 35.

In addition to storage costs, in some embodiments, holding a unit of anitem 35 in storage may incur capital or economic costs related to theprice paid to obtain the item. That is, once working capital or cashflow is committed to a unit of an item 35 (e.g., once that unit is paidfor), that economic value is not available for other purposes; thecommitted value is “tied up” in the corresponding inventory. Dependingon the accounting scheme used to manage the costs of inventory, a costof debt or other time-value-of-money cost (also referred to as aneconomic cost) may be associated with the price paid for a given unit ofan item 35. For example, in one embodiment an effective annual interestrate of 6% may be applied to the price paid for a unit of inventory andmay continue to accrue until that unit is sold or otherwise disposed of.In some embodiments, economic costs may be applied to storage costs inaddition to the price paid for a unit of inventory. In certain cases,negative economic costs may also be associated with units of items 35.For example, a supplier may offer a rebate for an item 35 thateffectively reduces its cost.

Other types of costs may also be associated with holding units of items35 in storage. For example, in the ordinary course of operation offulfillment center 10, items 35 may be subject to loss or damage due toaccidents or mishaps. A rate of loss, or a corresponding rate ofinsurance against such loss, may be included within an overall cost ofholding a unit of an item 35. Also, over time, items 35 may depreciate,expire, spoil or become obsolete, which may also be expressed as part ofa cost of holding such items 35.

Disposition Value and Inventory Health

As noted above, holding a larger inventory of an item 35 may betterenable an enterprise to absorb fluctuations in demand for that item.However, in some circumstances, the various elements of holding cost mayerode some of the advantages of holding inventory. For example, at agiven point in time, an enterprise may have at least two options withrespect to a unit of a particular item 35, as shown in FIG. 2. Theenterprise may hold the unit within fulfillment center 10 until it issold to a customer through a sales channel 200, or may dispose of theunit as soon as possible through a disposition channel 210. As describedin greater detail below, while a sales channel may generally yield ahigher price for a unit than a disposition channel, holding costs thataccrue until such a sale occurs may diminish the extra revenue received.

Generally speaking, sales channel 200 may encompass any suitable method,technique or relationship for conducting a transaction with a typicalcustomer of an enterprise, in response to an actual or expected customerorder or request. Sales channel 200 may include various featuresconfigured to present to customers information about items 35 (e.g.,availability and pricing information, product details, images, etc.) aswell as features configured to support the receipt and processing ofcustomer orders or requests. For example, a retail enterprise thatgenerally sells merchandise to end consumers (e.g., as merchandise notgenerally intended for resale as new) may sell through an online,web-based channel 200 that may include an online catalog or portalconfigured to display information about items 35, a web-based orderentry system such as a virtual shopping cart or other system, a statustracking tool through which customers may track the status or progressof orders, a search engine, or any of a number of other featuressuitable for promoting the conduction of sales transactions.

An enterprise may also engage in customer transactions using other typesof sales channels 200 or multiple such channels. For example, saleschannel 200 may encompass a catalog channel 200, through which customersmay receive information about items 35 via a catalog and provide ordersthrough physical order forms or via telephone, or a physical storechannel 200, through which customers may receive information about andorder or purchase items 35 in person. Manufacturers or distributors maysimilarly engage in sales of items 35 through sales channels 200appropriate to their position within the supply chain. It is noted thatin some embodiments, a unit of an item 35 may be rented, leased orlicensed to a customer via sales channel 200 under specific terms inexchange for revenue or other economic consideration. The term “sale”may be used herein to generically describe any suitable transactioninvolving an item 35 resulting in either direct or indirect (e.g.,imputed or tangential) revenue, and is intended to encompass rentals,leases, subscriptions, and other types of revenue models.

By contrast, disposition channel 210 may generally encompass anysuitable method, technique or relationship for disposing of units of anitem 35 as an alternative to sale through a sales channel 200. Invarious embodiments, a disposition channel 210 may include a vendorreturn channel through which units of an item 35 may be returned to avendor or supplier for credit, a liquidation channel through which unitsmay be liquidated through a third party, a salvage channel through whichunits may be disposed for scrap or salvage value, or a donation channelthrough which units may be donated, e.g., to a charitable cause. Inother embodiments, a disposition channel 210 may include a sales channelthat is an alternative to sales channel 200. For example, a dispositionchannel 210 may include a promotional sales channel through which unitsof an item 35 are offered at a discount (e.g., according to thecondition of the units, quantity on hand, or other relevant factors),bundled with units of other items 35 (e.g., as part of a “buy X, get Yfree” offer), offered for sale through an auction or bidding process,offered for sale through a promotional or marketing partner affiliatedwith the enterprise, or any other suitable disposition arrangement. Itis contemplated that in some embodiments, different terms and conditionsmay apply to a sale of an item 35 that occurs through a dispositionchannel 210 versus a sale that occurs through a sales channel 200. Forexample, a customer buying a unit of an item 35 via sales channel 200may receive certain return, exchange, warranty or satisfactionprivileges or guarantees that may not apply to purchases of that item 35through a disposition channel 210.

Generally speaking, the value of a unit of a given item 35 maycorrespond to the economic consideration that may be obtained for it viaa specific channel. For example, a unit of an item 35 may be sold viasales channel 200 for a particular price, which may be indicative of thevalue of a unit of item 35 with respect to sales channel 200. Bycontrast, a unit of an item 35 may be disposed of via dispositionchannel 210 for a different level of economic consideration. Forexample, the unit may be returned to a vendor for a percentage of theoriginal purchase cost of the unit, sold to a liquidator, or disposed ofvia any other suitable method such as described above. Economicconsideration received in exchange for an item 35 may typically includemonetary consideration, but may also include other consideration such ascredit relating to current or future transactions, bartered goods orservices, or any other form of value agreeable to the partiesparticipating in the exchange.

When considering revenue alone, it may often be preferable to sell agiven item 35 via sales channel 200 rather than to dispose of given item35 via a disposition channel 210. However, an enterprise may have littledirect control over when a sale event via sales channel 200 may occur,whereas an enterprise may have considerably greater control overinitiating disposition via a disposition channel 210. In certaincircumstances, holding costs that accrue until units of an item 35 aresold via sales channel 200 may reduce or even eliminate the differencebetween the sale value and the disposition value of the units.Consequently, even though greater revenue may be realized by waiting fora sale via sales channel 200 to occur, in certain circumstances overalleconomic value may be preserved or improved by electing to dispose ofunits of an item 35 via disposition channel 210.

By examining the value that may be received for a given item 35 viavarious channels in conjunction with the holding costs associated withgiven item 35, a breakeven holding time may be determined at whichholding costs approximately equal the difference in value between afuture sale and a current disposition of given item 35. The breakevenholding time may then be used to determine an inventory policy that maybe used to direct actions to be taken against items 35, such as whetherto hold or dispose of items 35.

At a general level of abstraction, the logic behind an inventory policythat takes into account a breakeven holding time may be summarized asfollows: Suppose an item 35 generally sells through a sales channel fora higher value than is expected to be received by disposing of the item35 through a disposition channel. Then, it may be expected that anygiven unit of item 35 may be profitably held for sale via the saleschannel until the costs of holding the unit approximately equal thedifference in value between the sales channel and the dispositionchannel. After this point, referred to as the breakeven holding time,accumulated holding costs may exceed the difference in value between thechannels. For example, a particular item 35 may have a sale value of tendollars and a disposition value of five dollars, and may incur holdingcosts of one dollar per week. Thus, the breakeven holding time for theparticular item 35 may be five weeks, at which time the accumulatedholding costs may be expected to total five dollars, equal to thedifference between the sale and disposition values.

The breakeven holding time may be used in determining a healthy level ofinventory. Generally speaking, a healthy level of inventory of an item35 may correspond to the total expected demand for that item 35 throughthe breakeven holding time. That is, if the breakeven holding timerepresents the “tipping point” for an item—the point at which holdingcosts may be expected to exceed the added value of selling the itemthrough a sales channel vs. a disposition channel—then the total amountof inventory of the item may be considered healthy (e.g., not at risk ofincurring excessive holding costs) if the inventory would be expected tobe sold via a sales channel prior to the breakeven holding time. Inother words, if the inventory on hand of an item is expected to “turnover” (e.g., be sold and possibly replaced) prior to the breakevenholding time, the inventory on hand may be considered healthy. Referringto the previous example, if the demand or sales rate of particular item35 is two units per week, then given the breakeven holding time of fiveweeks, a healthy inventory level for the particular item 35 may be tenunits.

In one embodiment, a breakeven holding time and a healthy inventorylevel for an item 35 may be determined as follows. Let ν and prespectively represent the disposition value associated with disposingof item 35 via disposition channel 210 (net of associated dispositioncosts) and the sale value associated with sale of item 35 via saleschannel 200, and let b represent the purchase paid to acquire item 35.If more than one disposition channel 210 exists, the disposition channel210 with the highest current disposition value may be chosen for theanalysis. Let h represent the rate of holding cost accrual for a unit ofitem 35 per unit of time (e.g., dollars per week). The total breakevenholding time T_(be) for item 35 may then be determined by setting theprofit realized from disposition of item 35 equal to the profit realizedfrom holding item 35 until the breakeven holding time and solving forT_(be). That is,νb=p−b−hT _(be).  (1)This yields

$\begin{matrix}{T_{be} = {\frac{p - v}{h}.}} & (2)\end{matrix}$

Given T_(be), the healthy inventory level H of item 35 may be determinedas follows:

$\begin{matrix}{{H = {\int_{0}^{T_{be}}{{D(t)}\ {\mathbb{d}t}}}},} & (3)\end{matrix}$where D(t) represents the demand (e.g., sales demand) for item 35 as afunction of time. That is, the definite integral of demand from time 0(e.g., the current time) through time T_(be) may represent the totalexpected demand over that interval of time, which may correspond to ahealthy inventory level. It is noted that in some embodiments, D(t) maybe given by a discrete rather than a continuous function.Correspondingly, discrete summation rather than integration may beemployed to determine H.

It is noted that in some embodiments, the accrued holding cost and thedifference between current sale and disposition value may not be exactlyequal, but rather equal within some equality threshold. That is, twovalues may be considered equal if their difference is less than theequality threshold, which may be expressed as an absolute value (e.g., agiven number of units) or a relative value (e.g., a percentage). Forexample, units of time or cost may not be arbitrarily divisible.Consequently, rounding or truncation of values may occur duringevaluation, which may lead to inexact computation.

In some embodiments, the healthy inventory level H and breakeven timeT_(be) may be determined relative to another inventory policy. Forexample, an enterprise may establish a target inventory level S of aparticular item 35 that may be used for planning and managing inventorylevels of that item 35. In some embodiments, S may be determined by anoptimization process configured to determine an optimal level ofinventory given various parameters, such as customer demand, supplierlead time, market dynamics, expected profit margins or other factors. Inother embodiments, S may simply be given as an arbitrary inventory leveltarget. Generally speaking, S may be determined in such a way that adesired service level for item 35 will be achieved for at least a periodof time T (the “coverage period”) with a given degree of certainty. Thatis, S may denote the amount of inventory needed to cover expected demandto the degree required by the desired service level (e.g., with acertain level of delay or other service parameters) for a period of timeT, with a certain probability or certainty. For example, the supply anddemand characteristics of a particular item 35 may be analyzed ormodeled to determine that 100 units of that item 35 are necessary toprovide two weeks of inventory coverage with a probability of 99%.

In some cases, the target inventory level S may not intrinsically takeinto account inventory health related to holding time, as describedabove. In one embodiment, a healthy inventory level may be determinedrelative to a target inventory level as follows. Let t_(be) representthe incremental breakeven holding time for an item 35 relative to T,That is,T _(be) =T+t _(be),  (4)although as noted below, in some instances t_(be) may be negative.Substituting equation (4) into equation (1) yieldsν−b=p−b−h(T+t _(be)),  (5)and solving for t_(be) yieldst _(be)=(p−ν−hT)/h,  (6)It is noted that alternative expressions and derivations are possible.In particular, it is noted that both equations (2) and (6), thebreakeven holding time is entirely independent of the purchase pricepaid to acquire item 35, b. Thus, the expression for breakeven holdingtime may also be derived by setting the total holding cost accrued untilthe breakeven holding time equal to the difference between the currentsale value and the current disposition value:p−ν=h(T+t _(be))  (7)

The relative breakeven holding time t_(be) may be generally illustrativeof a point in time beyond T at which accrued holding costs of an item 35begin to exceed the expected value from holding and eventually sellingitem 35 through a sales channel. Equations (3) and (4) may be combinedto yield an inventory health metric that reflects the disaggregation oftotal holding time T_(be) into a coverage period T and a relativebreakeven holding time t_(be) as follows:

$\begin{matrix}{H = {{\int_{0}^{T_{be}}{{D(t)}\ {\mathbb{d}t}}} = {{\int_{0}^{T}{{D(t)}\ {\mathbb{d}t}}} + {\int_{T}^{T + t_{be}}{{D(t)}\ {{\mathbb{d}t}.}}}}}} & (8)\end{matrix}$However, it is noted that the integral of expected demand over theinterval from 0 to T may reflect the accumulated demand throughout thecoverage period that is expected to be covered (within a degree ofcertainty) by the target inventory level S. Thus, equation (8) may berewritten as:

$\begin{matrix}{H = {S + {\int_{T}^{T + t_{be}}{{D(t)}\ {{\mathbb{d}t}.}}}}} & (9)\end{matrix}$

In some instances, the demand over the interval from T to T+t_(be) maybe given by an average value D. In such a case, equation (9) may befurther simplified to:H=S+Dt _(be).  (10)Generally speaking, in these formulations, the healthy inventory level Hmay exceed the target by the number of units expected to be sold,according to current demand D, over the incremental period of time givenby the breakeven holding period t _(be) . By substitution of equation(6), the healthy inventory level may be given in terms of sale channelvalue, disposition channel value, and holding cost accrual rate as:H=S+D(p−ν−hT)h.  (11)

According to the foregoing, a unit of item 35 that sells via saleschannel 200 after the breakeven holding time may yield a lower value,net of holding costs, than if it were disposed of via dispositionchannel 210. The number of units that may be expected to sell prior tothe breakeven holding time may generally be a function of the demand,and is reflected in the healthy inventory level as shown above. Itfollows that if a current inventory level I of an item 35 exceeds thehealthy inventory level H, for those units of item 35 in excess of thehealthy level, greater value may be realized by disposition viadisposition channel 210 rather than holding for sale via sales channel200. That is, those units in excess of H may be considered “unhealthy,”in that their value may be expected to be greater at the current timethan at some future time. It is noted that if the breakeven holdingperiod t_(be) is a negative value, all units in excess of targetinventory level S may be considered unhealthy. In this circumstance,accrued holding costs through the expected time of sale, given as hT,already equal or exceed the difference between the sale and dispositionvalues. Thus, in this case, H=S. In some instances, it may be possiblefor expected accrued holding costs for some units of S to equal orexceed the difference between the sale and disposition values, and thusbe technically “unhealthy.” However, in some embodiments, S may beenforced as a minimum required inventory level necessary to ensure agiven level of service. Consequently, in such embodiments, H may beconstrained to be greater than or equal to S.

As described above, in some embodiments, inventory management system 50may be configured to record and analyze the state of inventory items 35within fulfillment center 10. For example, inventory management system50 may be implemented as one or more software processes configured toexecute on one or more computer systems to create records of thearrival, storage, picking, sale, disposition or other events relating toitems 35 with respect to fulfillment center 10. In one embodiment,inventory management system 50 may be configured to analyze theinventory of a particular item 35, determine whether the inventory levelis healthy or unhealthy in accordance with the model derived above, andinitiate or suggest action, such as disposition, to be taken withrespect to any unhealthy inventory.

One embodiment of a method of analyzing inventory health is illustratedin FIG. 3. Referring collectively to FIGS. 1-3, operation begins inblock 300 where a target inventory level in units of a particular item35 is specified. As noted above, in various embodiments the target levelof inventory may be dynamically determined by any suitable algorithm orprocess, or may be statically or manually given. For example, inventorymanagement system 50 may be separately configured to determine thetarget level of inventory, may receive the target level from a differentsystem, or may include a static record or specification of the targetlevel.

Additionally, the time rate of sales demand of units of the particularitem 35 is determined (block 302). In one embodiment, inventorymanagement system 50 may extrapolate sales demand from historical salesactivity of the particular item 35. Alternatively, a more sophisticatedmodel internal or external to inventory management system 50 may beconfigured to generate a prediction of sales demand according tosuitable variables, such as seasonality, trends, planned marketing orpromotional activity, historical behavior of related items 35, futureproduct plans, or any other factor relevant to demand. As notedpreviously, sales channel 200 may generally encompass any suitable modelof revenue transaction, including rentals, leases, licensingarrangements, etc. Correspondingly, the time rate of sales demand maycorrespond to demand for any relevant type of transaction that may occurvia sales channel 200.

The breakeven holding time of units of particular item 35 in excess ofthe specified target inventory level is then determined (block 304).Specifically, as described above, the breakeven holding time may bedetermined such that the cost of holding a given excess unit until thebreakeven time equals, within an equality threshold, the differencebetween a current sale value for sale of the item 35 through a saleschannel 200 and a current disposition value for disposition of the item35 through a disposition channel 210. In one embodiment, inventorymanagement system 50 may be configured to determine current sale anddisposition value information and holding cost information for item 35or to obtain such information from another system, such as a pricing orfinance system.

A healthy inventory level of particular item 35 is then determined,where the healthy inventory level exceeds the target inventory level bythe product of the time rate of sales demand and the determinedbreakeven holding time, as described above (block 306). The currentinventory level of particular item 35 is then compared against thehealthy inventory level (block 308). If the current inventory level doesnot exceed the healthy inventory level, the inventory of particular item35 (including inventory in excess of the target inventory level, ifany), may be held for future sale (block 310). If the current inventorylevel does exceed the healthy level, those units of particular item 35in excess of the healthy level may be disposed of via dispositionchannel 210 (block 312). In one embodiment, inventory management system50 may be configured to generate a report or indication notifying a userof the system of the healthy or unhealthy status of inventory andadvising that a particular action (e.g., hold or dispose) be taken. Thatis, inventory management system 50 may merely advise or indicate that anaction such as disposition should be taken, while the actual undertakingof the indicated action is performed at the discretion of another agentor system. In other embodiments, inventory management system 50 may beconfigured to initiate the disposition process if unhealthy inventoryexists, for example by contacting a vendor to arrange a return,directing that unhealthy inventory be picked and packaged for return, orother actions suitable to disposition channel 210.

In some embodiments, more than one disposition channel 210 may exist,and such channels 210 may be limited in the number of units that can bedisposed of. For example, a vendor may limit the number of returns itwill accept to a given number or dollar value of units per month orother time period. Similarly, a liquidator may only accept a certainnumber of units at a given time. In some such embodiments, the method ofFIG. 3 may be applied to each disposition channel 210 in nonincreasingorder of disposition value. That is, each subsequent disposition channel210 to which the method is applied may have a disposition value that isless than or equal to the disposition value of the previous channel. Forexample, the highest value channel 210 may be selected to perform thebreakeven holding time analysis. If unhealthy inventory exists withrespect to the highest value channel 210, it may be removed frominventory to the extent that the limitations of the channel allow. Thenext highest-value channel 210 may then be selected for a similaranalysis, and the process may repeat until each disposition channel 210has been considered.

In the course of performing inventory health analysis, inventorymanagement system 50 may be configured to generate and report a numberof different inventory metrics that may be indicative of various aspectsof inventory decision quality and health status. For example, the totaloverstock amount I−S and associated purchase value b(I−S), dispositionvalue ν(I−S) and/or expected sale value p(I−S) may be reported. Similarmetrics may be reported with respect to unhealthy inventory I−H.Additionally, for unhealthy inventory, unit value loss speed (e.g.,given as the holding cost rate h) may be reported as an indication ofthe rate at which value loss increases due to continued holding costaccrual if disposition action is not taken. In some embodiments,inventory metrics may be defined for individual items 35 as well as inthe aggregate for groups of items, such as groupings by product type,manufacturer, etc. Additionally, in enterprises where different items 35may be associated with different business units or departments forfinancial or accounting purposes, metrics may be grouped and reportedaccording to organizational units. Numerous other types of inventorymetrics may also be generated.

Inventory Health Analysis of Purchase Opportunities

As described above, in one embodiment inventory management system 50 maybe configured to ascertain whether a given level of inventory of an item35 is healthy or unhealthy and to responsively initiate an appropriateaction, such as disposition of unhealthy inventory through a dispositionchannel 210. Such an analysis may be performed, for example, to managean existing quantity of inventory given its holding costs and salesdynamics. However, in some situations, an enterprise may be required todetermine whether a proposed inventory acquisition should be undertaken.

Generally speaking, just as units of a given item 35 may be sold ordisposed of through sales or disposition channels having associatedsales or disposition values, units of given item 35 may be acquiredthrough a purchasing channel for a purchase price or value. For example,a vendor, manufacturer or other supplier of inventory may present anoffer to an enterprise via a purchasing channel to purchase a particularnumber of units of a given item 35 for a particular price. Such an offermay be constrained in numerous ways: for example, the supplier mayrequire that a minimum quantity be purchased in order to receive apreferred offer price, or the supplier may require that the offer beaccepted within a specified time period. A supplier may furtherconstrain that units purchased according to the offer may haverestrictions on return or disposition options compared to unitspurchased under different terms. For example, units purchased under theterms of the offer may be not be returnable, may not be liquidated orresold through certain types of disposition channels 210, or otherrestrictions may apply. It is noted that, as described above withrespect to sales of items 35, the term “purchase” may refer to anysuitable type of acquisition transaction, including acquisitions ofrights or options, leases, rentals, licensing arrangements, etc.

Such offers may occasionally or frequently represent favorable deals foran enterprise in terms of the overall price paid for units of an item35. However, as noted above, holding costs of an item 35 may erode thevalue of item 35 over time, including any potential purchase savingsassociated with purchases under a constrained offer. If such purchasesare made without concern for overall inventory health, the enterprise'sgoal of maximizing inventory value may be frustrated. However, lengthyanalysis of the inventory health implications of an offer may result ina lost opportunity if the offer is not found to be acceptable before itexpires.

In the following discussion, methods and techniques are described inwhich the impacts of a particular purchasing opportunity for an item 35on the inventory health of that item 35 are analyzed. In one embodimentof such a method, a purchasing opportunity may be treated as ahypothetical disposition opportunity for the purposes of assessinginventory health implications. As described in detail below, if it wouldbe advantageous from an inventory health standpoint to dispose of item35 via such a hypothetical disposition (e.g., if some portion of theinventory of item 35 would be unhealthy with respect to such ahypothetical disposition channel), the purchasing opportunity may be illadvised. That is, it may be inadvisable to acquire inventory under termsfor which one would prefer to dispose of inventory, if the opportunityto dispose were available. In other embodiments of the method describedbelow, additional factors may be taken into account when evaluating apurchasing opportunity, such as determining whether minimum profitmargin requirements for the purchased units are expected to besatisfied, optimizing the purchase quantity, etc.

As described in the previous section, a given inventory level of an item35 may be considered unhealthy if greater value can be expected fromdisposing of at least some units of that item 35 via a dispositionchannel 210 instead of waiting for a sale to occur via a sales channel200. Generally speaking, a given inventory level may be either healthyor unhealthy with respect to any given disposition channel 210,according to the disposition value associated with the channel. That is,for any given disposition value, the given inventory level may be inexcess of the healthy inventory level, in which case disposition may beindicated, or below the healthy inventory level, in which caseadditional inventory may be accumulated without compromising inventoryvalue. (The given inventory level may also be equal to the healthyinventory level, in which case no additional inventory accumulation maybe advised, but inventory need not be disposed.)

For any given purchase offer for an item 35 that is being considered byan enterprise, the purchase price associated with the offer may beconsidered an indication of the value of item 35. If the currentinventory level of item 35 is unhealthy with respect to the purchaseprice, this would indicate that given an opportunity to do so (e.g.,given the existence of a disposition channel 210 having a dispositionvalue equal to the purchase price of the offer), inventory value may beimproved by disposition of units of item 35 for the value of thepurchase price. However, since disposition is the opposite ofacquisition, an indication that disposition for the value of thepurchase price is a preferable option may correspondingly indicate thatpurchasing for the indicated price is not preferable. In other words,given any particular value associated with an item 35 as well as thesales price, sales demand and holding cost characteristics describedabove, it would either be preferable to dispose of units of item 35 forthe particular value in question, or to hold those units for future sale(that is, current inventory of item 35 is either unhealthy or healthywith respect to the particular value). If it would be preferable todispose of units of item 35 in exchange for the particular value, a netacquisition of units of item 35 for the particular value may represent aquestionable opportunity. It is noted that no actual opportunity toperform a disposition for the particular value is necessary to concludethat a purchase would not be preferable. Rather, it is the potentialimpact to inventory health of disposition versus acquisition that maydetermine a preferable course of action.

Correspondingly, in one embodiment, inventory management system 50 maybe configured to analyze an offer to purchase units of an item 35 from asupplier as though the offer were actually an opportunity to dispose ofexisting inventory of item 35 for a disposition value equal to thepurchase offer price. That is, for the purposes of such an analysis,inventory management system 50 may be configured to treat a purchasingchannel as a disposition channel. If inventory management system 50determines that disposition would be indicated given the currentinventory state, the purchase offer may be declined.

One embodiment of a method of analyzing a purchasing opportunity withrespect to inventory health is illustrated in FIG. 4. Referringcollectively to FIGS. 1-4, operation begins in block 400 where an offerto purchase units of a particular item 35 via a purchasing channel for agiven purchase price per unit is received. Receiving a suitableindication specifying the details of the offer, such as a message, mayconstitute receiving the offer. The offer may or may not specify aminimum or maximum number of units eligible to be purchased. Forexample, inventory management system 50 may receive such an offerelectronically from a supplier. Alternatively, the offer may beelectronically received from or manually entered by a buyer for anenterprise who receives the offer from a supplier via another means.

Additionally, the time rate of sales demand of units of the particularitem 35 is determined (block 402). In various embodiments, sales demandmay be determined through appropriate extrapolation or modeling similarto that described above with respect to block 302 of FIG. 3.

The breakeven holding time of existing units of particular item 35(e.g., units of item 35 already held in inventory) beyond an expectedtime of sale of the existing units is then determined with respect tothe purchasing channel (block 404). The breakeven holding timedetermination may be similar to that described above with respect toblock 304 of FIG. 3, with the exception that the purchase pricespecified in the received offer may be used as the disposition value.That is, the purchasing channel corresponding to the received offer maybe treated as a disposition channel for the purposes of analyzing theoffer. Specifically, as described above, the breakeven holding time maybe determined such that the cost of holding a given excess unit untilthe breakeven time equals, within an equality threshold, the differencebetween a current sale value for sale of the item 35 through a saleschannel 200 and the given purchase price specified in the receivedoffer. In one embodiment, inventory management system 50 may beconfigured to determine current sale value information and holding costinformation for item 35 or to obtain such information from anothersystem, such as a pricing or finance system.

A healthy inventory level of particular item 35 with respect to thepurchasing channel is then determined, where the healthy inventory levelexceeds a target inventory level by the product of the time rate ofsales demand and the determined breakeven holding time, as describedabove (block 406). In some embodiments, the target inventory level maybe separately determined and treated as an input to the purchasingopportunity analysis.

The current inventory level of particular item 35 is then comparedagainst the healthy inventory level (block 408). If the currentinventory level exceeds the healthy inventory level as determined withrespect to the purchase price, the offer to purchase units of theparticular item 35 for the given purchase price may be declined (block410). In some embodiments, as described in greater detail below, acounteroffer may be made with respect to purchase price or quantity. Ifthe current inventory level does not exceed the healthy inventory level,the purchase price may be deemed acceptable (block 412). The offer maysubsequently be accepted, or evaluated with respect to purchase quantityas described below. Further evaluation may result in the offer beingaccepted or declined or a counteroffer being made. For example, if agiven offer that specifies a minimum purchase quantity is deemedunacceptable, in some embodiments the method of FIG. 4 may iterate overpossible purchase quantities to determine a purchase quantity that wouldbe acceptable at the offer price. Alternatively, the method of FIG. 4may iterate over possible offer prices to determine an offer price thatwould be acceptable at the minimum purchase quantity, or may iterateover both variables concurrently. It is noted that such iterations maytake into account any particular price or quantity increments that maybe implemented by a particular vendor. For example, a vendor may requirethat items 35 be ordered in certain multiples of units (e.g., crates,pallets, etc.) rather than individual units. Correspondingly, iterationover purchase quantities may reflect such multiples.

Once it has been determined that a purchase price associated with anoffer is acceptable with respect to the breakeven holding time analysisdescribed above, if no minimum purchase quantity is specified in theoffer, the number of units of item 35 to be purchased under the offermay be analyzed. According to the above analysis, if the purchase priceis deemed acceptable, the healthy inventory level H with respect to thepurchase price exceeds the current inventory level I. Thus, in oneembodiment, the quantity to be purchased under the offer may be anyquantity less than or equal to the difference H−I.

However, more sophisticated optimizations of purchase quantity relativeto the offer terms may be performed. In one embodiment, a minimum profitmargin M, in units of economic value (e.g., dollars) may be specifiedfor units of an item 35. For example, an enterprise may specify that aunit of item 35 should not be acquired or held unless there is areasonable expectation (e.g., justified by sales dynamics of item 35)that the unit will yield a profit margin of at least M. In variousembodiments, profit margin may take into account different factors andbe expressed or determined in different ways. For example, a minimummargin M may represent the difference between a sales price of a unit ofitem 35 and all aggregate costs associated with acquiring and holdingthat unit (e.g., its purchase price, holding costs, and/or otherassociated costs). In other approaches, some costs may be excluded froma margin determination, depending on accounting practices. While M maybe expressed in absolute terms, it may also be expressed as a relativepercentage m of another value, such as a purchase price paid or salesprice received for a unit of item 35 (indicated respectively as b and pin the above analysis). For example, in various embodiments, M=mb orM=mp. Other suitable definitions or derivations of profit margin mayalso be employed. It is noted that in some situations, it may bepermissible for profit margin to be negative, indicating a loss withrespect to an item 35. For example, an item 35 may be treated as a “lossleader” intended to catalyze other more profitable sales.

In one embodiment, the purchase quantity corresponding to a particularoffer, denoted Q, may be optimized given the constraint that thepurchased units should produce a minimum profit margin M relative to atotal available profit margin. Profit margin may typically be determinedaccording to a margin price basis, such as a purchase price paid, salesprice received, or a function of these or other prices. As describedabove, the costs of holding purchased units of an item 35 until salethrough sales channel 200 may erode the benefits of a higher sale valueversus a current disposition value. Such costs of holding may also erodethe realized profit margin for those units. Similar to the holdingbreakeven time described above, a profit margin breakeven time may bederived for item 35, where the cost of holding a given unit of item 35until the profit margin breakeven time equals all total available profitmargin except the minimum profit margin, within an equality threshold aspreviously discussed. That is, the cost of holding a unit is equal tothe total available margin less the minimum profit margin. For sake ofanalysis, suppose the total available margin is the expected sale pricep less the price corresponding to a particular purchasing opportunity oroffer, b (although it is noted that the basis of the total availablemargin calculation may be a function of either of these prices takenalone, or a more complex measure). According to one embodiment, theminimum profit margin according to a minimum margin rate m may be givenasM=m(p−b).  (12)Then, to determine the profit margin breakeven time, letht _(pm)=(1−m)(p−b),  (13)where h denotes holding costs per unit of time for a unit of item 35.Since accumulated holding costs should leave at least m percent of themargin basis, holding costs should not exceed 1−m percent of the marginbasis. The profit margin breakeven time, t_(pm), is then given as

$\begin{matrix}{t_{pm} = {\frac{\left( {1 - m} \right)\left( {p - b} \right)}{h}.}} & (14)\end{matrix}$

As before, the average time rate of sales demand of units of item 35 maybe given as D. (For simplicity of exposition, the simple average ofdemand is used for the following derivations. However, it is noted thatalternate expressions, using integral or summation techniques similar tothose employed in previous derivations, may be developed that make useof a continuous or discrete functional expression of demand D(t). Suchgeneral expressions are contemplated as within the scope of thefollowing discussion.) The optimal quantity of units to be purchasedunder the terms of the offer being considered may be given as Q*. If thelast unit purchased is expected to yield the minimum profit margin, thenthe total number of units in inventory following a purchase should notexceed the number expected to be sold before the profit margin breakeventime. Thus,I+Q*=Dt _(pm).  (15)Solving for Q* and substituting for t_(pm) yields

$\begin{matrix}{Q^{*} = {\frac{\left( {1 - m} \right)\left( {p - b} \right)D}{h} - {I.}}} & (16)\end{matrix}$

Generally speaking, a purchase should not result in inventory of an item35 exceeding healthy inventory level H for that item. This constraintcan be made explicit in the calculation of Q*:

$\begin{matrix}{Q^{*} = {{\min\left( {{H - I},{\frac{\left( {1 - m} \right)\left( {p - b} \right)D}{h} - I}} \right)}.}} & (17)\end{matrix}$

Once the purchase quantity has been optimized with respect to a desiredminimum profit margin, it is possible to determine the net contributionto overall profit that may be expected from executing the purchase. Fromthe above analysis, the last unit of the purchase quantity, when sold,has a net profit contribution of m(p−b) and is sold after Q*/D timeelapses, incurring hQ*/D in holding costs. Correspondingly, the firstunit of the purchase quantity, if sold before any substantial holdingcosts accrue, should contribute hQ*/D+m(p−b) to the net profit. Inembodiments where sales demand is linear over time, the total net profitcontribution V* of the units purchased under the terms of the purchaseoffer may be computed as the average of the contributions of the firstand last units sold multiplied by the number of units purchased:

$\begin{matrix}{V^{*} = {{\frac{1}{2}\left( {{{hQ}^{*}/D} + {m\left( {p - b} \right)} + {m\left( {p - b} \right)}} \right)Q^{*}} = {\left( {\frac{{hQ}^{*}}{2D} + {m\left( {p - b} \right)}} \right){Q^{*}.}}}} & (18)\end{matrix}$In other embodiments, total net profit contribution from the purchasemay be computed using other techniques, such as by summing orintegrating profit contributions of individual units or groups of unitssold.

It may be the case, in some circumstances, that a supplier may makepurchase price b contingent upon an enterprise purchasing a minimumquantity Q of units of an item 35. If, after optimizing for a particularminimum profit margin, the optimized purchase quantity Q* is greaterthan or equal to the minimum required quantity Q, quantity Q* may bepurchased without further consideration. However, if Q*<Q, furtheranalysis may be required to determine whether the overall profitcontribution of the purchase is still acceptable. As before, the firstunit of the purchase quantity sold should still contribute hQ*/D+m(p−b)towards the net profit of the entire purchase. The last unit of thepurchase quantity sold will be held for a time of Q/D and incur holdingcosts of hQ/D relative to the first unit sold, for a net profitcontribution of hQ*/D+m(p−b)−hQ/D (i.e., the profit contribution of thefirst unit sold less the cost of holding the last unit until it issold). Once again, if sales demand is linear, the total net profitcontribution V for the case of purchasing Q units, where Q*<Q, may bedetermined by averaging the contributions of the first and last unitssold:

$\begin{matrix}{\begin{matrix}{V = {\frac{1}{2}\left( {{{hQ}^{*}/D} + {m\left( {p - b} \right)} + {{hQ}^{*}/D} + {m\left( {p - b} \right)} - {{hQ}/d}} \right)Q}} \\{{= {{{hQ}^{*}/D} + {m\left( {p - b} \right)}}}\;}\end{matrix}.} & (19)\end{matrix}$or by other suitable summation techniques. Whether to engage in thepurchase may then be made on the basis of V. For example, if V is withina certain percentage or amount of V*, the purchase may be made for aquantity Q despite the fact that Q*<Q. In some embodiments, if V isunacceptable, a counteroffer may be made. For example, the enterprisemay counteroffer with a purchase quantity of Q* rather than Q.Alternatively, the equations given above may be rearranged to solve forthe purchase price b that would yield an acceptable profit V for theminimum purchase quantity Q, and the enterprise may counteroffer with arevised purchase price b. The enterprise may also choose to negotiateother aspects of the purchase, such as credit or delivery terms, or maysimply choose to decline the offer. Generally speaking, whether a givenexpected profit is acceptable may depend on whether the given expectedprofit satisfies an acceptability criterion. Such a criterion may berepresented as an absolute amount or as a percentage or relation, forexample relative to purchase price, sales price or some other value. Anacceptability criterion may also include a function that encompassesother variables or metrics, such as sales projections, sales velocity,marketing plans, or other suitable factors that may influence a decisionwhether to accept or decline an offer.

As described above with respect to FIG. 4, inventory management system50 may be configured to analyze an offer to purchase units of an item 35from a supplier as to the inventory health implications of such apurchase. Similarly, in one embodiment inventory management system 50may be configured to optimize the quantity of units to be purchasedunder the terms of a given purchase offer with respect to a minimumprofit margin requirement. In one such embodiment, inventory managementsystem 50 may also be configured to determine a net profit contributionassociated with the optimized purchase quantity of units, as well as anet profit contribution associated with a minimum required purchasequantity, if any. In some embodiments, inventory management system 50may also be configured to recommend counteroffer strategies if apurchase offer is found unacceptable, such as by recommendingalternative purchase prices or quantities.

One embodiment of a method of analyzing a purchasing opportunity withrespect to purchase quantity and price is illustrated in FIG. 5.Referring collectively to FIGS. 1-5, operation begins in block 500 wherea minimum profit margin associated with a particular item 35 isspecified. For example, an enterprise may impose a uniform requirementor expectation that all items 35 yield a profit margin of some amount orpercentage. Alternatively, different profit margin expectations may beimposed for different types of items 35, such as product classes (e.g.,books, music, electronics, appliances, etc.), brands, specific productlines, or individual items 35. It is noted that, as mentioned above,profit margin may be determined in any suitable, consistent fashion, forexample as an absolute dollar amount, as a percentage of a purchaseprice or sale price, as a percentage of gross profit (e.g., a differencebetween a sale price and a purchase price), etc.

Additionally, the time rate of sales demand of units of the particularitem 35 is determined (block 502). In various embodiments, sales demandmay be determined through appropriate extrapolation or modeling similarto that described above with respect to block 302 of FIG. 3.

An offer to purchase units of a particular item 35 via a purchasingchannel for a given purchase price per unit is received (block 504). Asin block 400 of FIG. 4, the offer or a suitable indication of the offer(e.g., a message including the offer details) may be received byinventory management system 50 electronically or by other means, and mayor may not specify a minimum purchase quantity. It is noted that in someembodiments, the method of FIG. 5 may be performed after the offer hasbeen analyzed with respect to inventory health as described above withrespect to FIG. 4. In some such embodiments, analysis of the offeraccording to FIG. 5 may be performed contingent upon whether purchase ofany quantity of item 35 would render inventory unhealthy with respect tothe purchasing channel as described with respect to FIG. 4.

The profit margin breakeven time of particular item 35 is thendetermined with respect to the offer (block 506). In one embodiment, asdescribed above, inventory management system 50 may be configured todetermine the profit margin breakeven time such that the accrued cost ofholding a unit of particular item 35 purchased under the offer until theprofit margin breakeven time equals, within an equality threshold aspreviously described, the difference between the total available profitmargin for particular item 35 (e.g., according to the basis on whichmargin is computed) less the minimum profit margin associated withparticular item 35. For example, the total available margin may be givenas the difference between a sales price and the purchase offer price,p−b, and the minimum profit margin may be given as m(p−b). Thedifference between these, as described above, may be given as(1−m)(p−b).

The purchase quantity of units of particular item 35 may then beoptimized with respect to the profit margin breakeven time (block 508).In one embodiment, inventory management system 50 may be configured todetermine an optimized purchase quantity Q* of particular item 35according to the previously determined profit margin breakeven time andthe time rate of sales demand of particular item 35, as described indetail above. In some embodiments, if the optimized purchase quantity asdetermined on this basis is greater than the difference between thecurrent inventory level I of particular item 35 and a healthy inventorylevel H (as determined with respect to the purchase channel, e.g.,according to the method of FIG. 4), the difference H−I may be selectedas the optimized purchase quantity of particular item 35, as describedabove.

The total expected contribution to net profit of the optimized number ofunits subject to purchase under the terms of the offer may then becomputed (block 510). For example, inventory management system 50 may beconfigured to compute the net profit V* as the average of the profitcontributions of the first and last units sold times the number of unitspurchased, where the last unit sold has an expected profit contributionof the minimum profit margin and the first unit sold has an expectedprofit contribution of the minimum profit margin plus the accruedholding cost until the profit margin breakeven time of the last unitsold, as described above. In other embodiments, other types of summationor integration techniques may be used to compute the expected net profitof units of particular item 35 purchased under the terms of the offer.

If a minimum purchase quantity Q is specified by the terms of thepurchase offer, and the minimum quantity is less than or equal to thepreviously determined optimized purchase quantity Q* (applying anappropriate equality threshold if necessary), or if no minimum purchasequantity is specified, the optimized purchase quantity may be purchased(blocks 512-514). If the minimum purchase quantity is greater than Q*,the total contribution to net profit of the minimum purchase quantity ofunits Q may be computed (blocks 512-516). For example, inventorymanagement system 50 may be configured to compute the net profit of theminimum quantity of units V by averaging the profit contributions of thefirst and last units sold in a manner similar to that described abovefor block 510, with the exception that the profit contribution of thelast unit sold may be reduced by its holding costs for holding time inexcess of the profit margin breakeven time, as described previously.This step is not necessarily contingent upon a comparison of the minimumpurchase quantity with the optimized purchase quantity. For example,determination of the net expected profit of the minimum purchasequantity of units V may be performed concurrently with the computationof V in block 510, in some embodiments.

If the net expected profit associated with the minimum purchase quantityQ is acceptable relative to the net expected profit associated with theoptimized purchase quantity Q*, the minimum required quantity of unitsmay be purchased (blocks 518-520). For example, if the difference V*−Vis less than some absolute or relative threshold quantity (e.g., as apercentage of V*), the offer may be deemed acceptable. In this case,inventory management system 50 may be configured to autonomouslyinitiate or complete the purchasing process, or to advise another entity(e.g., an employee or other agent) that the offer is acceptable andshould be pursued.

If the net expected profit associated with the minimum purchase quantityQ is not acceptable, the offer may be declined, or, in some embodiments,a counteroffer may be made (blocks 518-522). For example, in someembodiments inventory management system 50 may be configured todetermine a counteroffer purchase price that would render the netexpected profit acceptable with respect to the minimum purchasequantity, or conversely, to determine a counteroffer purchase quantitythat would render the net expected profit acceptable with respect to thepurchase offer price. In some embodiments, inventory management system50 may be configured to autonomously reject an offer or negotiate acounteroffer with a supplier, or to advise another software or humanagent of the strategy that should be employed. Also, in some embodimentsa purchase offer may still be accepted even though the net expectedprofit associated with the minimum purchase quantity Q is not acceptableand no counteroffer is agreed to. For example, such a purchase offer maybe deliberately accepted for exceptional reasons that go beyond theanalysis factors and logic programmed into inventory management system50. Such exceptional reasons may include, for example, competitivestrategy (e.g., to prevent a competitor from acquiring resources),vendor goodwill, public relations, charitable activity or any otherfactors not captured by the inventory management model.

It is noted that in some embodiments, not all steps of the method shownin FIG. 5 may occur. For example, if no minimum purchase quantity isspecified for a purchase offer, blocks 516 through 522 may be omitted.Also, counteroffer logic may be omitted from inventory management system50, such that purchase offers are simply rejected if a minimum purchasequantity exceeds the optimized purchase quantity Q* at block 512.

Exemplary Computer System Embodiment

It is contemplated that in some embodiments, any of the methods ortechniques described above may be implemented as program instructionsand data capable of being stored or conveyed via a computer-accessiblemedium. Such methods or techniques may include, for example and withoutlimitation, the functions of inventory management system 50, as well asthe methods illustrated in FIGS. 3, 4 and 5 and any suitable variationsthereof. Such program instructions may be executed to perform aparticular computational function, such as inventory health metricgeneration and analysis, purchase offer analysis, purchase and/or salesmanagement, operating system functionality, applications, and/or anyother suitable functions.

One exemplary embodiment of a computer system includingcomputer-accessible media is illustrated in FIG. 6. In the illustratedembodiment, computer system 900 includes one or more processors 910coupled to a system memory 920 via an input/output (I/O) interface 930.Computer system 900 further includes a network interface 940 coupled toI/O interface 930. In some embodiments, it is contemplated thatinventory management system 50 may be implemented using a singleinstance of computer system 900, while in other embodiments multiplesuch systems may be configured to host different portions or instancesof inventory management system 50. For example, in one embodiment somedata sources or services (e.g., purchasing management services) may beimplemented via instances of computer system 900 that are distinct fromthose instances implementing other data sources or services (e.g., orderentry/fulfillment services).

In various embodiments computer system 900 may be a uniprocessor systemincluding one processor 910, or a multiprocessor system includingseveral processors 910 (e.g., two, four, eight, or another suitablenumber). Processors 910 may be any suitable processor capable ofexecuting instructions. For example, in various embodiments processors910 may be a general-purpose or embedded processor implementing any of avariety of instruction set architectures (ISAs), such as the x86,PowerPC, SPARC, or MIPS ISAs, or any other suitable ISA. Inmultiprocessor systems, each of processors 910 may commonly, but notnecessarily, implement the same ISA.

System memory 920 may be configured to store instructions and dataaccessible by process 910. In various embodiments, system memory 920 maybe implemented using any suitable memory technology, such as staticrandom access memory (SRAM), synchronous dynamic RAM (SDRAM),nonvolatile/Flash-type memory, or any other type of memory. In theillustrated embodiment, program instructions and data implementingdesired functions, such as those described above, are shown storedwithin system memory 920 as code 925.

In one embodiment, I/O interface 930 may be configured to coordinate I/Otraffic between processor 910, system memory 920, and any peripheraldevices in the device, including network interface 940 or otherperipheral interfaces. In some embodiments, I/O interface 930 mayperform any necessary protocol, timing or other data transformations toconvert data signals from one component (e.g., system memory 920) into aformat suitable for use by another component (e.g., processor 910). Insome embodiments, I/O interface 930 may include support for devicesattached through various types of peripheral buses, such as a variant ofthe Peripheral Component Interconnect (PCI) bus standard or theUniversal Serial Bus (USB) standard, for example. In some embodiments,the function of I/O interface 930 may be split into two or more separatecomponents, such as a north bridge and a south bridge, for example.Also, in some embodiments some or all of the functionality of I/Ointerface 930, such as an interface to system memory 920, may beincorporated directly into processor 910.

Network interface 940 may be configured to allow data to be exchangedbetween computer system 900 and other devices attached to a network,such as other computer systems, for example. In various embodiments,network interface 940 may support communication via wired or wirelessgeneral data networks, such as any suitable type of Ethernet network,for example; via telecommunications/telephony networks such as analogvoice networks or digital fiber communications networks; via storagearea networks such as Fibre Channel SANs, or via any other suitable typeof network and/or protocol.

In some embodiments, system memory 920 may be one embodiment of acomputer-accessible medium configured to store program instructions anddata as described above. However, in other embodiments, programinstructions and/or data may be received, sent or stored upon differenttypes of computer-accessible media. Generally speaking, acomputer-accessible medium may include storage media or memory mediasuch as magnetic or optical media, e.g., disk or CD/DVD-ROM coupled tocomputer system 900 via I/O interface 930. A computer-accessible mediummay also include any volatile or non-volatile media such as RAM (e.g.SDRAM, DDR SDRAM, RDRAM, SRAM, etc.), ROM, etc, that may be included insome embodiments of computer system 900 as system memory 920 or anothertype of memory. Program instructions and data stored via acomputer-accessible medium may be transmitted by transmission media orsignals such as electrical, electromagnetic, or digital signals, whichmay be conveyed via a communication medium such as a network and/or awireless link, such as may be implemented via network interface 940.

Additionally, it is contemplated that any of the methods or techniquesdescribed above and illustrated, for example, in FIGS. 3-5 may beimplemented as a web service that may be performed on behalf of clientsrequesting such a service. Generally speaking, providing a function orservice as a web service may encompass providing any of a variety ofstandardized APIs configured to allow different software programs tocommunicate (e.g., to request services and respond to such requests) inan autonomous, web-based and typically platform-independent manner. Forexample, an enterprise may choose to expose certain enterprise data(e.g., catalog data, inventory data, customer data or other types ofdata) and/or certain enterprise functions (e.g., query functions,electronic commerce functions, generic data storage or computationalfunctions, etc.) to external customers (or, in some embodiments,internal clients) via a web services interface. Applications could thenaccess the exposed data and/or functions via the web services interface,even though the accessing application may be configured to execute on anentirely different platform (e.g., a different operating system orsystem architecture) than the platform hosting the exposed data orfunctions. Similarly, an enterprise may elect to provide clients withaccess to inventory management analysis services, such as inventoryhealth determination, purchase offer analysis, counteroffer analysis orother such services. For example, clients may provide inventory detailsvia a web services interface and request various kinds of analysisthrough that interface. Alternatively, an enterprise may elect toprovide physical management of inventory on behalf of clients, and mayanalyze client-owned inventory in a manner similar to enterprise-ownedinventory, exposing the results of such analysis to clients as a webservice.

In some embodiments, provisioning a web service may encompass the use ofparticular protocols which may be executable (e.g., as part of code 925)to publish available web services to potential users, to describe theinterfaces of web services sufficiently to allow users to invoke webservices properly, to allow users to select and differentiate among webservices for a particular transaction, and to provide a format forexchanging web services data in a flexible and platform-independentmanner. Specifically, in one embodiment a provider of a web service mayregister the service using a version of the Universal DiscoveryDescription and Integration (UDDI) protocol, which may function as ageneral directory through which potential resource users may locate webservices of interest. The web service provider may also publish specificdetails regarding how a well-formed web services request from a usershould be formatted (e.g., what specific parameters are required orallowed, the data type or format to be used for a given parameter,etc.). For example, such interface details may be published (e.g.,within a UDDI directory entry) using a version of the Web ServicesDescription Language (WSDL).

In many embodiments, web services request and response data is exchangedbetween a client and the service provider through the use of messages ordocuments formatted as platform-independent structured data, such as adocument formatted in compliance with a version of eXtensible MarkupLanguage (XML). For example, in one embodiment a web services request toprovide inventory health information for a given inventory item may beembodied in an XML document including fields identifying the item ofinterest, the type of data requested (e.g., inventory health data), andpossibly other fields, in which each field is delimited by an XML tagdescribing the type of data the field represents. The response to such arequest from the web service provider may include an XML documentcontaining the requested data. In some embodiments, web services-relateddocuments may be transmitted between applications making requests andtargeted web services using a web-based data transfer protocol, such asa version of the Hypertext Transfer Protocol (HTTP), for example.

Different types of web services requests and responses may yield XMLdocuments that bear little content in common, which may complicate thehandling and interpretation of such documents. For example, in differentversions of a free-form XML document specifying a web services request,the actual web service that is requested may appear at different placeswithin different document versions, which may require a recipient of thedocument to buffer or parse a good deal of document data beforeunderstanding what the document is for. Consequently, in someembodiments, the XML documents containing web services request/responsedata may encapsulated within additional XML data used to define amessaging framework, e.g., a generic format for exchanging documents ormessages having arbitrary content. For example, in one embodiment webservices requests or responses may be XML documents formatted accordingto a version of the Simple Object Access Protocol (SOAP), which invarious versions may define distinct document sections such as an“envelope” (e.g., which may include a specification of the documenttype, the intended recipient web service, etc.) as well as a messagebody that may include arbitrary XML message data (e.g., the particulardetails of the web services request). However, in some embodiments, webservices may be implemented using different protocols and standards forpublishing services and formatting and exchanging messages.

Additionally, in some embodiments, a web services system may beimplemented without using document-based techniques such as SOAP-typeprotocols. For example, as an alternative to a document-based approach,a web service may be implemented using a Representational State Transfer(REST)-type architecture. Generally speaking, in REST-typearchitectures, web services requests may be formed as commands conveyedvia a transport protocol, such as PUT or GET commands conveyed via aversion of the HTTP protocol. Those parameters of the request that mightbe embedded within a document in a document-based web servicesarchitecture may instead be included as command parameters in aREST-type architecture. Other suitable configurations of web servicesarchitectures are possible and contemplated.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations and modifications.

1. A method, comprising: receiving an offer to purchase units of aninventory item via a purchasing channel for a given purchase price perunit; determining a breakeven holding time of existing units of saidinventory item, wherein a cost of holding a given existing unit untilsaid breakeven holding time equals, within an equality threshold, adifference between a sale value for sale of said given inventory itemthrough a sales channel and said given purchase price specified by saidoffer; determining a time rate of sales demand of units of saidinventory item per unit of time; determining a healthy inventory levelof said inventory item, wherein said healthy inventory level exceeds atarget inventory level by a function of said time rate of sales demandand said breakeven holding time; in response to determining that acurrent inventory level of said inventory item exceeds said healthyinventory level, declining to purchase said units of said inventory itemfor said given purchase price; wherein each of said receiving an offer,said determining a breakeven holding time, said determining a time rateof sales demand, said determining a healthy inventory level, and saiddeclining to purchase is performed by one or more computers.
 2. Themethod as recited in claim 1, wherein said time rate of sales demand isrepresented as an average rate of sales demand, and wherein saidfunction includes a multiplicative product of said time rate of salesdemand and said breakeven holding time.
 3. The method as recited inclaim 1, wherein said time rate of sales demand is represented as acontinuous function in time, and wherein said function includes anintegral of said continuous function bounded by said breakeven holdingtime.
 4. The method as recited in claim 1, wherein said time rate ofsales demand is represented as a discrete function in time, and whereinsaid function includes a summation of said discrete function boundedsaid breakeven holding time.
 5. The method as recited in claim 1,further comprising purchasing a particular number of units of saidinventory item in response to determining that said current inventorylevel of said inventory item does not exceed said healthy inventorylevel, wherein said particular number is less than or equal to adifference between said healthy inventory level and said currentinventory level.
 6. The method as recited in claim 1, wherein said costof holding said given existing unit of said given inventory itemincludes a cost of storing said given existing unit.
 7. The method asrecited in claim 1, wherein said cost of holding said given existingunit of said given inventory item includes an economic cost of capitalassociated with a purchase price of said given existing unit.
 8. Amethod, comprising: receiving an offer to purchase units of an inventoryitem via a purchasing channel for a given purchase price per unit;determining a breakeven holding time of existing units of said inventoryitem, wherein a cost of holding a given existing unit until saidbreakeven holding time equals, within an equality threshold, adifference between a sale value for sale of said given inventory itemthrough a sales channel and said given purchase price specified by saidoffer; determining a time rate of sales demand of units of saidinventory item per unit of time; determining a healthy inventory levelof said inventory item, wherein said healthy inventory level exceeds atarget inventory level by a function of said time rate of sales demandand said breakeven holding time; in response to determining that acurrent inventory level of said inventory item exceeds said healthyinventory level declining to purchase said units of said inventory itemfor said given purchase price; specifying a minimum profit marginassociated with said inventory item; determining a profit marginbreakeven time of said inventory item, wherein a cost of holding a givenunit of said inventory item until said profit margin breakeven timeequals, within an equality threshold, a total available profit marginassociated with said inventory item less said minimum profit margin; anddetermining an optimized purchase quantity of units of said inventoryitem dependent upon a multiplicative product of said profit marginbreakeven time and said time rate of sales demand of units of saidinventory item; wherein each of said receiving an offer, saiddetermining a breakeven holding time, said determining a time rate ofsales demand, said determining a healthy inventory level, said decliningto purchase, said specifying a minimum profit margin, said determining aprofit margin breakeven time, and said determining an optimized purchasequantity is performed by one or more computers.
 9. The method as recitedin claim 8, further comprising determining a total expected profit fromsale of said optimized purchase quantity of units dependent upon anaverage of a first profit contribution associated with a first-sold oneof said optimized purchase quantity of units and a second profitcontribution associated with a last-sold one of said optimized purchasequantity of units.
 10. The method as recited in claim 9, wherein saidfirst profit contribution exceeds said second contribution by an accruedcost of holding said last-sold one of said optimized purchase quantityof units until said profit margin breakeven time.
 11. The method asrecited in claim 8, wherein said offer specifies a minimum purchasequantity of units of said inventory item, and wherein the method furthercomprises determining whether said minimum purchase quantity of unitsexceeds said optimized purchase quantity of units.
 12. The method asrecited in claim 11, further comprising purchasing said optimizedpurchase quantity of units in response to determining that saidoptimized purchase quantity of units exceeds or equals said minimumpurchase quantity of units.
 13. The method as recited in claim 11,further comprising declining said offer in response to determining thatsaid minimum purchase quantity of units exceeds said optimized purchasequantity of units.
 14. The method as recited in claim 11, furthercomprising: in response to determining that said minimum purchasequantity of units exceeds said optimized purchase quantity of units,determining a counteroffer purchase quantity of units for which anexpected profit associated with said counteroffer purchase quantity ofunits satisfies an acceptability criterion; and presenting acounteroffer to said offer, wherein said counteroffer specifies saidcounteroffer purchase quantity of units.
 15. The method as recited inclaim 11, further comprising: in response to determining that saidminimum purchase quantity of units exceeds said optimized purchasequantity of units, determining a counteroffer purchase price per unitfor which an expected profit associated with said counteroffer purchaseprice per unit satisfies an acceptability criterion; and presenting acounteroffer to said offer, wherein said counteroffer specifies saidcounteroffer purchase price per unit.
 16. A computer-accessible mediumcomprising program instructions, wherein the program instructions areexecutable to: receive an indication of an offer to purchase units of aninventory item via a purchasing channel for a given purchase price perunit; determine a breakeven holding time of existing units of saidinventory item, wherein a cost of holding a given existing unit untilsaid breakeven holding time equals, within an equality threshold, adifference between a sale value for sale of said given inventory itemthrough a sales channel and said given purchase price specified by saidoffer; determine a time rate of sales demand of units of said inventoryitem per unit of time; determine a healthy inventory level of saidinventory item, wherein said healthy inventory level exceeds a targetinventory level by a function of said time rate of sales demand and saidbreakeven holding time; in response to determining that a currentinventory level of said inventory item exceeds said healthy inventorylevel, indicate that said offer to purchase said units of said inventoryitem for said given purchase price should be declined.
 17. Thecomputer-accessible medium as recited in claim 16, wherein said timerate of sales demand is represented as an average rate of sales demand,and wherein said function includes a multiplicative product of said timerate of sales demand and said breakeven holding time.
 18. Thecomputer-accessible medium as recited in claim 16, wherein said timerate of sales demand is represented as a continuous function in time,and wherein said function includes an integral of said continuousfunction bounded by said breakeven holding time.
 19. Thecomputer-accessible medium as recited in claim 16, wherein said timerate of sales demand is represented as a discrete function in time, andwherein said function includes a summation of said discrete functionbounded said breakeven holding time.
 20. The computer-accessible mediumas recited in claim 16, wherein said program instructions are furtherexecutable to indicate that a particular number of units of saidinventory item should be purchased in response to determining that saidcurrent inventory level of said inventory item does not exceed saidhealthy inventory level, wherein said particular number is less than orequal to a difference between said healthy inventory level and saidcurrent inventory level.
 21. The computer-accessible medium as recitedin claim 16, wherein said program instructions are further executableto: specify a minimum profit margin associated with said inventory item;determine a profit margin breakeven time of said inventory item, whereina cost of holding a given unit of said inventory item until said profitmargin breakeven time equals, within an equality threshold, a totalavailable profit margin associated with said inventory item less saidminimum profit margin; and determine an optimized purchase quantity ofunits of said inventory item dependent upon a multiplicative product ofsaid profit margin breakeven time and said time rate of sales demand ofunits of said inventory item.
 22. The computer-accessible medium asrecited in claim 21, wherein said program instructions are furtherexecutable to determine a total expected profit from sale of saidoptimized purchase quantity of units dependent upon an average of afirst profit contribution associated with a first-sold one of saidoptimized purchase quantity of units and a second profit contributionassociated with a last-sold one of said optimized purchase quantity ofunits.
 23. The computer-accessible medium as recited in claim 22,wherein said first profit contribution exceeds said second contributionby an accrued cost of holding said last-sold one of said optimizedpurchase quantity of units until said profit margin breakeven time. 24.The computer-accessible medium as recited in claim 21, wherein saidoffer specifies a minimum purchase quantity of units of said inventoryitem, and wherein said program instructions are further executable todetermine whether said minimum purchase quantity of units exceeds saidoptimized purchase quantity of units.
 25. The computer-accessible mediumas recited in claim 24, wherein said program instructions are furtherexecutable to indicate that said optimized purchase quantity of unitsshould be purchased in response to determining that said optimizedpurchase quantity of units exceeds or equals said minimum purchasequantity of units.
 26. The computer-accessible medium as recited inclaim 24, wherein said program instructions are further executable toindicate that said offer should be declined in response to determiningthat said minimum purchase quantity of units exceeds said optimizedpurchase quantity of units.
 27. The computer-accessible medium asrecited in claim 24, wherein said program instructions are furtherexecutable to: in response to determining that said minimum purchasequantity of units exceeds said optimized purchase quantity of units,determine a counteroffer purchase quantity of units for which anexpected profit associated with said counteroffer purchase quantity ofunits satisfies an acceptability criterion; and indicate that acounteroffer to said offer should be presented, wherein saidcounteroffer specifies said counteroffer purchase quantity of units. 28.The computer-accessible medium as recited in claim 24, wherein saidprogram instructions are further executable to: in response todetermining that said minimum purchase quantity of units exceeds saidoptimized purchase quantity of units, determine a counteroffer purchaseprice per unit for which an expected profit associated with saidcounteroffer purchase price per unit satisfies an acceptabilitycriterion; and indicate that a counteroffer to said offer should bepresented, wherein said counteroffer specifies said counterofferpurchase price per unit.
 29. The computer-accessible medium as recitedin claim 16, wherein said cost of holding said given existing unit ofsaid given inventory item includes a cost of storing said given existingunit.
 30. The computer-accessible medium as recited in claim 16, whereinsaid cost of holding said given existing unit of said given inventoryitem includes an economic cost of capital associated with a purchaseprice of said given existing unit.
 31. A system, comprising: a systemmemory storing program instructions; and a processor coupled to saidsystem memory and configured to execute said program instructions,wherein said program instructions are executable to: receive anindication of an offer to purchase units of an inventory item via apurchasing channel for a given purchase price per unit; determine abreakeven holding time of existing units of said inventory item beyondan expected time of sale of said existing units, wherein a cost ofholding a given existing unit until said breakeven holding time equals,within an equality threshold, a difference between a current sale valuefor sale of said given inventory item through a sales channel and saidgiven purchase price specified by said offer; determine a time rate ofsales demand of units of said inventory item per unit of time; determinea healthy inventory level of said inventory item, wherein said healthyinventory level exceeds a target inventory level by a multiplicativeproduct of said time rate of sales demand and said breakeven holdingtime; in response to determining that a current inventory level of saidinventory item exceeds said healthy inventory level, indicate that saidoffer to purchase said units of said inventory item for said givenpurchase price should be declined.
 32. A method, comprising: receiving aweb services request to analyze an offer to purchase units of aninventory item via a purchasing channel for a given purchase price perunit; in response to receiving said web services request, determining abreakeven holding time of existing units of said inventory item, whereina cost of holding a given existing unit until said breakeven holdingtime equals, within an equality threshold, a difference between a salevalue for sale of said given inventory item through a sales channel andsaid given purchase price specified by said offer; determining a timerate of sales demand of units of said inventory item per unit of time;determining a healthy inventory level of said inventory item, whereinsaid healthy inventory level exceeds a target inventory level by afunction of said time rate of sales demand and said breakeven holdingtime; in response to determining that a current inventory level of saidinventory item exceeds said healthy inventory level, generating aresponse to said web services request, wherein said response includes anindication advising to decline to purchase said units of said inventoryitem for said given purchase price; wherein each of said receiving a webservices request, said determining a breakeven holding time, saiddetermining a time rate of sales demand, said determining a healthyinventory level, and said generating a response is performed by one ormore computers.